Meet Machimosaurus rex, a Giant New Dinosaur-era Crocodile

Cretaceous North Africa was a bit like the Texas of its day; everything just seemed to be that little bit bigger there, especially when it comes to predators. The Sahara of the Cretaceous was home to several species of meat eating dinosaurs in the T. rex size bracket including Carcharodontosaurus, Bahariasaurus and Sauroniops. Things wouldn’t have gotten any much safer if you took refuge in a nearby river or lake though, as an even bigger predatory dinosaur named Spinosaurus aegyptiacus was amphibious and spent most of its time hunting in or around water. If Spinosaurus didn’t get you, then chances are one of two species of crocodiles which exceeded 10 metres in length (Stomatosuchus and Sarchosuchus) might well have.

Machimosaurus rex illustration by Davide Bonadonna.

But wait, there’s more! A third type of massive Cretaceous North African croc has just been announced by palaeontologist Federico Fanti and his team, who excavated its bones in Southern Tunisia in December 2014. This one, named Machimosaurus rex, was different to the aforementioned crocodiles as it lived about 20 million years beforehand and was a sea-faring croc from a family (the teleosuchidae) which was previously believed to have gone extinct at the end of the Jurassic.

Several species of Machimosaurus are known from late Jurassic deposits all over Europe. The genus seemed to thrive until a perceived extinction event at the end of the Jurassic period wiped out their lineage – or so it was thought. The discovery of Machimosaurus rex in early Cretaceous deposits shows that, far from succumbing to extinction, the teleosuchidae lived on and grew larger than ever. The biggest species of teleosuchid (before the discovery of M. rex) was Machimosaurus hugii, from Switzerland, which grew to lengths in the region 9 metres. M. rex, by contrast, was closer to 10 metres long, with a full body length of 31 feet from the tip of its long snout to the end of its tail, and a weight of about 3 tons. To put that into perspective, the biggest recorded example of a modern day crocodile was a record-breaking saltie caught in 2012 in the Philippines which was just over 6 metres long and weighed a little over 1 ton.

The teeth of Machimosaurus rex were somewhat rounded and blunted, indicating that it spent much of its life at sea hunting turtles. Its jaws would also have been exceptionally strong, meaning that it could most likely have taken on land-lubbing prey as well. Modern saltwater crocodiles are not picky about what they eat and often ambush unsuspecting terrestrial animals at the shore where land meet sea. It is easy to imagine a creature of Machimosaurus‘ great size and strength doing similar with small to medium sized dinosaurs.

Detailed view of Machimosaurus rex‘s skull with full body size comparison to human (the parts of the animal’s skeleton which have been discovered are highlighted) by Marco Auditore.

Sean is Geek Ireland's resident dinosaur enthusiast, having been fascinated by prehistory since a time before he could read, speak or stand in an upright position (he still struggles to do at least one of these things on a daily basis).
Known as one of the biggest dinosaur fans Ireland has ever produced, Sean has delivered talks on his favourite subject at many venues and events including the Irish Film Institute, the UCD Science Expression Festival, Tayto Park, Dublin Comic Con and even London's Comedy Store.